Rotary hammer.



H M. PhMSTED.

ROTARY HAMMiR.

APPLICATION mw mm at. 19m.

Pan-11ml A pr. 22, 1919.

HAROLD I. I'LAISTED, 0F GRANITE CITY, ILLINOIS.

ROTARY HAMMER.

Specification of Letters Patent.

Patented Apr. 22, 1919.

Application filed June 17, 1918. Serial ll'o. 840,898.

To all whom itmay concern:

Be it known that I, HAROLD M. PLAISTED, a citizen of the United States,residing at Granite City, in the county of Madison and State ofIllinois, have invented certain new and useful Improvements in RotaryHammers, of which the following is a specificalion.

This invention relates to certain new and useful improvements in arotary hammer, the peculiarities of which will be hereinafter describedand claimed.

The main object of my invention is the provision of a rotar hammerhaving one or more wide operative edges and a shank of small relativethickness compared to its width set transversly to said edges like a T,so as to present comparatively little surface to the material beingreduced, and to provide means for avoiding interference between saidhammers.

In the accompanying drawing on which like reference letters indicatecorresponding parts, Figure 1 represents a partial transverse sectionalelevation of a reducing machine embodying my invention; Fig. 2 a partialsection of the cage taken in an opposite direction, showing thepreferred relation of my rotary hammers by an ed view of theirperiphery; Fig. 3 a detail ace view of a shank of my hammer with its Thead; Fig. 4 a similar side edge view of the shank and T head; and Fig.5 a top view of the head shown in Figs. 3 and 4.

The letter A designates an arcuate cage of any suitable form concentricwith a shaft B on which are fastened hammer mounts, preferablyconsisting of disks C--C supporting hammer rods D on which are pivotedrotary hammers, the pivot 'ends of which are mounted in suitable pocketsS formed in said disks.

These hammers consist of flat bar shanks, or other shape in which thethickness is comparatively small with regard to the width. The hammer isso mounted that only this lesser dimension or edge thickness ispresented to the material operated on during the forward rotation of thehammer. One end of said shank is provided with a pivot hole E, or othermeans for pivotally mounting said hammer. There are preferably two ofsaid holes, the other hole E, being located the same distance on theopposite side of a lon itudinal central line F through said shank, as isthe center of said hole E.

At the other end of said shank there is provided a cross piece extendinglaterally outward from each face of said shank in opposits directionsand substantially the same distance, so as to form a T head. The lateralpro1ections forming said T-head extend out ward substantially at rightangles to the flat faces of the shank; and are likewise of lesserthickness, measured radially throu h the pivot, than the Width measuredin t e plane of rotation. The narrow side dimension or radial edgethickness of these lateral projections forming the head is presented tothe material being reduced, similarly to the presentation of the sideedge of the flat bar shank. By forming a T-head and shank on myrinciple, none of the flat or width of the ar is presented to thematerial being reduced, but only the side edge thickness or lesserdimension of said bar. My hammer therefore tends to slice through thematerial being reduced; and likewise tends to avoid carrylng around withthe hammer the material'being operated on, as is the tendency with ahammer in which any of the flat, or width of a fiat bar is presentedtoward the material being reduced. This cross piece is preferably zigzagin plan view as shown in Fig. 5, and is preferably formed, when of thiszigzag shape, by splitting the outer end of said shank for a portion ofthe length along the longitudina center line. and then forcing therespective halves of said end over in opposite directions until they aresubstantially at right angles to each face of said shank, and with eachedge on the respective halves substantially equi-distant from therespective pivot hole center, measured diagonally across said centralline F. In a quarter twist hammer the head and shank at the junction arenot directl presenting the lesser dimension of the ar to the materialbeing reduced, but inevitably present part of the width of the shank tothe material at the junction of head and shank, and thereby carry aroundwith the hammer some of the material and obstruct the slicing actionthat is desired. It is to overcome this objection in a previous form ofhammer in which the head and shank are connected by a quarter twist,that the present T-head is formed directly extending laterally outwardon each side of the flat bar shank, substantially as shown. In thiszigzag form of T-head in which the cross plate forms the Thead, theoperative edges on each side of the shank are 'not directly alined butare zigzag in the preferred form. The cross piece plate head may beotherwise formed however. Four operative edges are thus formed on saidcross piece two edges on said sides of the shank G-G being separatedsubstantially the width of the shank, and the other two operative edgesbeing substantially in line with each other and traversing the centralline F. In Fig. 3 full lines have been drawn from center of the hole Eto the operative edges H and I at the side G, and the center line F,respectively. These lines indicate that these operative edges aresubstantially equi-distant from the center of the hole E. The dashedlines in the same figure indicate that the operative edges J and Krespectively adjacent to the side G and the central line F are likewisee iii-distant from the center of the hole E. Ihis arrangement of theoperative ed s causes the cross piece forming the T hea to assume theshape of two bevels as shown in Fig. 3. The action of a forgin machinein forming hammers of this kin will readily swage the split end of thehammer into the shape desired so that the operative edges will besubstantially as shown in the drawing.

As will be seen by reference to Fig. 1, the forward operative ed e H isin front of a radial line L from t e shaft through the ivot center E,and the edge I-K is a little hind said radial line,when said hammer isin its normal position under rotation. Thus said forward edges H and Iof the T head are substantially the same distance from the ca A, whilethe rear edge J is a further distance from said cage, due to the bevelof said 1' head and to the eccentric location of the pivot center E.When said hammer is reversed and mounted on the pivot hole E the edges Jand K come into similar operation.

The operative ed es above described may be of any kind an shape desiredthat is, they may be sharp as shown in Fig. 1 throughout their length,or may be serrated with an under cut saw-tooth shape as shown in Figs.3, 4 and 5; or may be otherwise formed. When the front edges H and I areof saw-tooth shape they are especiall adapted to cutting alfalfa andlike material: and by their increased length of cutting edge facilitatethe cutting action and make the power required for rotating the hammer'smuch less than other form of cutting edge. Alfalfa mills however have atendency to thrown out the material entering the mill, and I havetherefore shown the edges J and K as plain or square edge in Fig. 3. andthe edges H and I in the opposite direction being formed with saw teeth.When a hammer of this design is mounted in disks as shown in Fig. 2,that

is, with the forward edges of one hammer plain and the following hammerwith the forward edges serrated,the action of the hammers is to draw inas well as to cut the alfalfa or like material.

While the forward edge of a hammer of my construction only presents thelesser dimension or edge thickness of the bar to the material being cutand allows the cutting edges to operate upon the material and passthrough said material with little obstructions, it is dmirable to extendthe cutting edge opposite the sides G and G so as not to lose thebenefit of the thickness of the bar. This I do by means of a cut-out ornotch M by which the bevel of the operative edge, H for instance, iscarried past and through the thickness of the-bar. In the use of asaw-tooth edge, this notch M would be sharpened, as shown at M Figs. 3and 4, to avoid the alfalfa collecting on the side of the shank.

In a previous construction shown in Patent No. 1,281,829, dated Oct.15th, 1918, I have likewise shown two pivot holes in the end of a rotaryhammer and have claimed them broadly in connection with the operati veedges there shown.

In Fig. 1 is shown a bearing edge P, and a bearin edge Q, located resectively beyond, an inside, of the pivot o the hammer in its pocket Sformed b a cut-out openin in the adjacent disk. hese edges in sai pocketare ada ted to contact with the side G of said shan and with a contactsurface R at the inner end of said shank, ectively, and thus form stopsfor the oscillation of said hammer in both directions. It is especiallynecessary to limit the oscillation of hammers havin sharpredges andprevent two hammers hittin each other when one or both rebound, an thusdulling said edges. I avoid such interference by providing the bearingsurfaces P and Q located on the wall of the ket as shown in thisapplication. It wil be noted that the bearing surface Q and the contactsurface R, that meet when the hammer is on a rebound from the dottedposition shown in Fig. 1, are both located radially inside of the pivoton which the hammer is then operating, but are on the op osite side of aradius from the center of t e shaft through said pivot, from the stop orbearing surface P of said pocket. In my 1115 lication above referred to,I have shown such stop surfaces as both located on the same side of theivot, but in a hammer of the construction s own in which the end that ispivoted is substantially square, I have claimed the location and stopsurfaces as shown in this application.

I claim I. A rotary hammer comprising a flat bar shank having two holesat one end for pivotal mounting,said holes being located on oppositesides of a central longitudinal line,and a T-head on said shank havingfour operative ed es extending transversely in opposite directions fromthe faces of said shank,each pair of said edges being substantiallyequiistant from the center of the respective ivot holes, measureddiagonally auross t e central longitudinal line.

2. A rotary hammer comprising a fiat bar shank having a pivot hole atone end and a zi zag cross iece forming a T-head at the 0 er end, saidhead having four operative edges,two of said edges being se arated bysubstantially the width of said ank, and the other two edges beingsubstantially alined with each other and extending in oppositedirections from the respective face of said shank.

3. A rotary hammer comprising a flat bar shank having a pivot hole nearone end, and provided with a T-head having a saw-tooth cutting edgeadjacent to one side of said shank, and a plain edge ad'aeent to theother side of said shank, su ntially as and for the purpose described. 7

4. A rotary hammer comprising a flat bar shank, havin a pivot hole nearone end, and provided at the other end with a T- head having anoperative cutting edge adjacent to one side of said shank,-said shankbeing sharpened for a portion of the side adjacent to said head,substantially as descri 5. The combination with a rotary pivot hammerhaving art of a side radiall beyond its pivot a apted for contact, ananother part of the hammer radially inside of the pivot but on the oposits side of a central line through said shank also adapted forcontact, of a disk having a pocket for the pivot end of said hammer,saidpocket having bearing edges forming stops limiting the oscillation ofsaid hammer and pre venting interierence with adjacent hammere andlocated radially beyond said pivot, and radially inside of said pivotrespectively but on opposite sides of a radial line from the shaftthrough said ivot, respectively, substantially as described? Intestimony whereof I have aflixed my signature. Y

HAROLD M. PLAISTED.

